Digital Graphics File Formats

Liam Allan

Raster Graphics

Raster graphics are images that are constructed of square shaped pixels of many different colours. Raster graphics are captured e.g. by a camera, scanner etc. Or created in an image creation software and the image’s information is mapped across a grid meaning that a raster graphic cannot be edited without a loss of quality for instance if you were to attempt to upscale a raster graphic (right) the original already has a fixed resolution and therefore when upscaled a clear loss of quality can be observed.

Vector Graphics

Vector graphics are constructed of paths and lines (as appose to pixels), some curved some straight. These paths and lines contain the data of where each point starts and end and also, if necessary, how much they curve as well as the colours that surround or take up the line. Due to the fact that the images are constructed of lines and paths as appose to pixels they can be freely transformed without loss of quality as they do not have any fixed characteristics therefore when up scaling a vector graphic there is no loss in quality as the data in the image will fit to the new conditions it has been given.

Raster Graphics

JPEGStands For Joint Photographic Group

Used For/Example JPEG’s are quite commonly used in photography as cameras typically have the option to shoot in JPEG or RAW.JPEGs are also a very popular choice for websites as their file size is such a small amount meaning that slower connections are able to download this image

and therefore experience the website a lot faster.

Advantage When JPEG’s are shot on cameras they do not require specialist software but rather just a simple file that can be opened, transferred etc. with easeSmaller file sizes so can be easily accessed online with a slow connection and created due to the more available space.

Disadvantage Loses quality very easily so they cannot be edited multiple times.Fixed statistics such as resolution making this a very restricted file type

TIFFStands For Tagged Image File Format

Used For/Example TIFF is an image file format used when transferring raster graphics through different applications for instance faxing: An image is scanned on the first machine to which it is stored on a TIFF and printed out on the other machine. TIFF’s are most commonly used in: Website/Desktop publishing, faxing (as mentioned), photography etc.

Advantage -Does not perform compression meaning quality is not compromised during edits.-Multiple documents can be stored on a single file.-Recognised by the vast majority of editing software's

Disadvantage -Due to the absence of compression the file types tend to be on the larger side meaning this file type is less popular to people with less free space.

GIFStands For Graphics interchange Format

Used For/Example A GIF is a collection of images that play one after the other to create a form of video/animation much like the way a film works by playing many frames.GIF’s are most commonly used on the internet on social media, however they are used in a more professional environment for instance product illustrations tend to use GIF’s in order to demonstrate how said product will function.

Advantage -GIF’s are a smaller file size meaning theycan be used as an alternative to videos on websites for people with a slow download speed.-GIF’s are also supported by all web browsers.

Disadvantage -GIF’s are heavily compressed meaning quality is always degraded -GIF’s are restricted to 256 colours meaning a more complex image will appear significantly different

BMPStands For Bitmap Image File

Used For/Example A bitmap is composed on square pixels known as bits which contain colour information and are at a fixed resolution (left). Bitmap graphics are very out-dated and were used on older PC’s and websites by developers

Advantage -Easy to use in scenarios in which an image is not to be rescaled or resized such as PowerPoint presentations, websites etc.

Disadvantage -Fixed resolution meaning rescaling degrades quality meaning edits cannot be performed without the loss of quality.-Larger file size as the computer has to store the image of each bit.

Vector Graphics

PSDStands For Photoshop Documents

Used For/Example PSD files are the format in which aPhotoshop project is saved. Photoshop is used for image manipulation for projects such as magazine covers, digital art etc.

Advantage -Multiple layers, effects etc. are saved in one file.-PSD’s supports transparency

Disadvantage -Only recognised by Photoshop and nothing else-If a project uses many layers and effects the file size can become very large.

AIStands For Adobe Illustrator

Used For/Example An AI is the same concept as a PSD but for Adobe Illustrator as appose to Photoshop. Adobe Illustrator is used to create vector images which are often used for company logos, charts, graphs etc. Meaning this file type is most commonly used for business purposes as appose to personal

Advantage -Uses vector based images meaning rescaling, recolouring and general edits can be performed with no loss of quality.-Multiple edits can be saved in one file as appose to many.

Disadvantage -To create this file you need to use Adobe Illustrator which requires specialist software.-File can only be read by Adobe Illustrator meaning it’s diversity is extremely limited.

FLAStands For Flash File

Used For/Example Flash Files are used to create multiple media such as videos and game which are most commonly seen on the internet meaning web and or game developers are most likely to use this file.

Advantage -Flash files can include audio as well as just visual.-If made correctly flash files create a high quality, professional looking product.

Disadvantage -Cannot be edited once created-Flash files are only accessible via computers as appose to mobile devices which are significantly more popular-When used online the page tends to load a lot slower

WMFStands For Windows Metafile

Used For/Example Windows metafile’s were created by Microsoft for their computers throughout the 90s. These are rarely used today but were used mainly by users of Microsoft PC in the 1990’s.

Advantage -Due to Metafiles being code based they require less memory than bitmaps (which were also mostly used at this time).-The vast majority of metafiles were vector based as appose to raster based.

Disadvantage -Incredibly out-dated today as images can be simply constructed in image editing software.-Supported by few software in the 90s and almost none today.

File Format Capture and Optimising

CompressionDefinition Compression is when an image is resized

or altered in any other way which means the information from the image is “compressed” which can cause the loss of the previous information and thus a lower quality picture.

Advantage If an image is compressed successfully it means it will have a much smaller file size depending on the amount of compression that has taken place which in itself brings in many separate benefits depending on the project.

Disadvantage If the image is not a vector based graphic the compression will remove the image’s overall quality which will not be able to recovered. For example Microsoft Paint is bitmap based and as mentioned earlier raster graphics do not re create the image information like vector graphics (left).

Image CaptureMethod Scanner

How is it used for image capture of graphics

Scanners use both mirrors and a lamp to capture the image.Firstly an image is placed in the scanner and the cover closed to which it is “scanned” by the scanner head which is made of two mirror, the first reflects the image into the other and the second reflects the image into the capture device. A scanner is often used to transfer hard paper documents to a digital format which an efficient way of cutting corners in terms of time and is commonly used for business and or artistic purposes.

Method Camera

How is it used for image capture of graphics

When the button is pressed on a digital camera an aperture opens up to which light is brought in and reflected through a mirror onto the digital capture device (which is the same as the one used in a scanner) called a CCD. Cameras are used professionally by photographers but to capture media camera’s can be used to capture papers images such as drawings in order to transfer them to a digital format

Method Graphics Tablet

How is it used for image capture of graphics

A graphics tablet is touch screen based and can be either wired or wireless. When using a graphics tablet a stylus is required which the user draws an image on the tablet that appears on the computer screen. These are used as a form of digital substitute to paper as it cuts out having to transfer the image to a digital format, working digitally also opens up many doors in

terms of enhancements when creating images.

OptimisingWhy would you optimise? Optimising images are most often used for web images in

order to enhance quality and file sizes, another important aspect is file types as if the wrong file type is used the stability and speed of the website will drastically decrease which is more than likely to reduce the amount of visitors to the website.

How can you optimise? Firstly in terms of size images must be saved at the desired dimensions that they will be posted on the website with as if they are not it will make the website “heavier” in terms of content thus causing slower loading times. Secondly files must be one of three file types which are JPEG, GIF and PNG as these files can be easily compressed for the internet. The three file types are used for different purposes which are JPEG’s being still images, GIF’s being a collection of images played back and finally PNG’s for images with transparent

backgrounds.

Advantage to optimising -Optimising images will give a website a very much more stable and fast experience which will potentially result in more visitors.-Image optimisation results in a website have a much more organised and professional appearance as the sizes and file types will be correct.

Disadvantage to optimising -Optimising an images size has to be saved at the ideal dimensions otherwise it will slow down the website which means extra time is added to a websites development due to specific dimensions being required.-The three file sizes that are recommended are compressed for use online which can result in degraded quality.